While Microsoft touts the 1.0 version Silverlight as a powerful vehicle for delivering hi-def video and rich content over the Web, the 1.1 version of the plug-in -- now in alpha -- is broader in scope. It delivers a version of the Common Language Runtime and includes support for dynamic languages, with the idea being that developers can code RIA apps for multiple platforms with Microsoft's managed code framework and dev tools.

Microsoft put out the 1.0 beta at its MIX07 conference in the spring. According to Sneath, the dev team has since done work resulting in "a few breaking changes between the beta and release candidate."

Microsoft has prepared a special SDK, which will help those who have created apps with the beta release to get ready for the RC, according to Sneath: "To be clear, this preview release does not contain the Silverlight 1.0 RC itself; it's a bit of a chicken-and-egg situation in that we want to get sites ready before we release the RC, but it's hard for folk to be sure they're ready until we release the RC!"

Sneath noted that "moving forward, the API is stable: there should be no further breaking changes between the release candidate and the final release."

Though Microsoft has stressed the cross-platform nature of Silverlight, to date it has not provided a Linux version. However, a team led by Miguel de Icaza, Novell's vice president of development, has already demoed a version of the plug-in running on a Linux system.